Automatic gain control devices techniques involve adjusting the output audio power of an audio stream based on the deviation of the audio power from some target value. For example, if the audio power of an audio stream is below a target value, gain is increased, and if the audio power of an audio stream is above a target value, the gain is decreased. In a conference session, the target value may be based on an average power of all participants of an audio session in an attempt to make all participants “equal” in terms of the audio power of each participant. Current automatic gain control techniques consider each voice stream independently and do not adjust the target power of audio streams based on their interactions with one another.
However, even when all gains are roughly equal, acoustic or psychological effects can cause some participants to dominate an audio conference, while other participants are placed at a disadvantage. Participants with loud voices, low-gain earpieces or loudspeakers, poor hearing, or even intense concentration on what they are saying, can miss normal auditory cues that would allow their speech to be interrupted. Similarly, participants with soft voices, high-gain earpieces or loudspeakers, or who are unusually sensitive to interruptions, can be preempted from speaking. Because the audio conference bridge will only mix a small number of simultaneous speakers, typically 2 or 3, which are selected based on those speakers which have the most voice energy at the conference bridge, additional effects may occur. For example, when quiet participants are mixed simultaneously, they often will talk over each other, since the ambient acoustic sound of each participant's voice is much louder than the mixed sound of the other low-gain voices that are returned over the audio channel. The result is that no speaker obtains a good audio cue that there has been a collision. In contrast, when a quiet speaker and a louder speaker speak simultaneously, the louder speaker's voice is more likely to register with the quiet speaker's ear.
In many audio and video conference meetings, some participants' inputs are more necessary than others. A way of biasing the gain applied at a conference bridge so that certain participants are more likely to be heard can greatly improve meeting productivity.